The prior art provided various methods and apparatus for measuring the concentration of glycosylated hemoglobin in a blood sample. These methods principally required microcolumn devices for chromatographic separation of the blood sample fractions. Typically, the blood samples were separately lysed before passage through the microcolumn. The microcolumn contained an ion exchange resin that binds and separates the various hemoglobin fractions released by lysis of the blood cells as the lysate passes through the column.
For instance, U.S. Pat. No. 4,270,921 to Grass, issued June 2, 1981 relates to a microchromatographic device and a method for determining the relative concentration of glycosylated hemoglobin present in the red blood cells of a person. This reference discloses the use of a microcolumn device which contains an eluent buffer containing a blood cell lysing agent and an ion exchange resin capable of separating out the glycosylated hemoglobin species present in the blood cell lysate. Although both of these components are enclosed within the device, they perform their functions at different locations, with the lysis of the blood cells taking place before the lysate passes through the resin and out into a separate container.
U.S. Pat. No. 4,238,196 to Acuff et al, granted Dec. 9, 1980, discloses a method for measuring glycosylated hemoglobin utitlizing a liquid chromatographic column wherein the blood cells are lysed prior to passage through the column.
U.S. Pat. No. 4,168,147 to Acuff granted Sept. 18, 1979, and U.S. Pat. No. 4,142,858 to Acuff granted Mar. 6, 1979, also relate to methods for measuring glycosylated hemoglobin in a blood sample by utilizing liquid chromatographic microcolumns.
The prior art has also disclosed other methods which required secondary reactions for measuring the glycosylated hemoglobin content in a blood sample.
U.S. Pat. No. 4,268,270 to Gabbay et al granted May 19, 1981, relates to a method and apparatus for measuring glycosylated hemoglobin content of a blood sample wherein blood cells are first lysed with distilled water prior to analysis and then the glycosylated hemoglobin fraction is oxidized to generate aldehydic compounds. The extent of the presence of generated aldehydic compounds are then measured to indicate the amount of glycosylated hemoglobin present.
The prior art has also disclosed various methods and apparatus whose stated use was limited to separating the components of a whole blood sample the blood cells of which have not been lysed. One particular type of device, which fits onto a test-tube in a cap-like manner, injects a silicone type material into the test tube while the tube containing the blood sample is being centrifuged. The silicone type material acts to form a barrier between the accretion solids forced to the bottom of the tube by the centrifugal force and the liquid supernatant remaining above the solids. Glycosylated hemoglobin, however, cannot be released into the supernatant unless the whole blood is lysed prior to centrifugation and this is not suggested by the prior art. The following references U.S. Pat. Nos. 4,230,584 to Ichikawa et al; 4,140,631 to Okuda et al; and 3,780,935 to Lukas et al, all relate to this type of device for use only with separating a whole blood sample into its component parts, serum and whole red blood cells.
There is now provided by the present invention a method and apparatus for separating and measuring the amount of glycosylated hemoglobin in a blood sample which overcomes the limitations of the prior art.
It is, therefore, an object of the present invention to provide a non-chromatographic apparatus for separating a glycosylated hemoglobin fraction from a blood sample.
It is another object of the present invention to provide a meethod for measuring the amount of a glycosylated hemoglobin in a blood sample which is determinative of the relative amount of said hemoglobin present in the blood sample source.
The aforesaid as well as other objects and advantages will be made more apparent in reviewing the attached drawings and in reading the following description and the adjoined claims.